feat(core): Add GOOGLE_GENAI_API_VERSION environment variable support

docs/cli/configuration.md

@@ -476,6 +476,10 @@ the `excludedProjectEnvVars` setting in your `settings.json` file.
   - If set to `bearer`, the API key will be sent in the
     `Authorization: Bearer <key>` header.
   - Example: `export GEMINI_API_KEY_AUTH_MECHANISM="bearer"`
+- **`GOOGLE_GENAI_API_VERSION`**:
+  - Specifies the API version to use for Gemini API requests.
+  - When set, overrides the default API version used by the SDK.
+  - Example: `export GOOGLE_GENAI_API_VERSION="v1"`
 - **`GOOGLE_API_KEY`**:
   - Your Google Cloud API key.
   - Required for using Vertex AI in express mode.

packages/core/src/core/contentGenerator.test.ts

@@ -338,6 +338,152 @@ describe('createContentGenerator', () => {
       new LoggingContentGenerator(mockGenerator.models, mockConfig),
     );
   });
+
+  it('should pass apiVersion to GoogleGenAI when GOOGLE_GENAI_API_VERSION is set', async () => {
+    const mockConfig = {
+      getModel: vi.fn().mockReturnValue('gemini-pro'),
+      getProxy: vi.fn().mockReturnValue(undefined),
+      getUsageStatisticsEnabled: () => false,
+      getPreviewFeatures: vi.fn().mockReturnValue(false),
+    } as unknown as Config;
+
+    const mockGenerator = {
+      models: {},
+    } as unknown as GoogleGenAI;
+    vi.mocked(GoogleGenAI).mockImplementation(() => mockGenerator as never);
+    vi.stubEnv('GOOGLE_GENAI_API_VERSION', 'v1');
+
+    await createContentGenerator(
+      {
+        apiKey: 'test-api-key',
+        authType: AuthType.USE_GEMINI,
+      },
+      mockConfig,
+    );
+
+    expect(GoogleGenAI).toHaveBeenCalledWith({
+      apiKey: 'test-api-key',
+      vertexai: undefined,
+      httpOptions: {
+        headers: expect.objectContaining({
+          'User-Agent': expect.any(String),
+        }),
+      },
+      apiVersion: 'v1',
+    });
+  });
+
+  it('should not include apiVersion when GOOGLE_GENAI_API_VERSION is not set', async () => {
+    const mockConfig = {
+      getModel: vi.fn().mockReturnValue('gemini-pro'),
+      getProxy: vi.fn().mockReturnValue(undefined),
+      getUsageStatisticsEnabled: () => false,
+      getPreviewFeatures: vi.fn().mockReturnValue(false),
+    } as unknown as Config;
+
+    const mockGenerator = {
+      models: {},
+    } as unknown as GoogleGenAI;
+    vi.mocked(GoogleGenAI).mockImplementation(() => mockGenerator as never);
+
+    await createContentGenerator(
+      {
+        apiKey: 'test-api-key',
+        authType: AuthType.USE_GEMINI,
+      },
+      mockConfig,
+    );
+
+    expect(GoogleGenAI).toHaveBeenCalledWith({
+      apiKey: 'test-api-key',
+      vertexai: undefined,
+      httpOptions: {
+        headers: expect.objectContaining({
+          'User-Agent': expect.any(String),
+        }),
+      },
+    });
+
+    expect(GoogleGenAI).toHaveBeenCalledWith(
+      expect.not.objectContaining({
+        apiVersion: expect.any(String),
+      }),
+    );
+  });
+
+  it('should not include apiVersion when GOOGLE_GENAI_API_VERSION is an empty string', async () => {
+    const mockConfig = {
+      getModel: vi.fn().mockReturnValue('gemini-pro'),
+      getProxy: vi.fn().mockReturnValue(undefined),
+      getUsageStatisticsEnabled: () => false,
+      getPreviewFeatures: vi.fn().mockReturnValue(false),
+    } as unknown as Config;
+
+    const mockGenerator = {
+      models: {},
+    } as unknown as GoogleGenAI;
+    vi.mocked(GoogleGenAI).mockImplementation(() => mockGenerator as never);
+    vi.stubEnv('GOOGLE_GENAI_API_VERSION', '');
+
+    await createContentGenerator(
+      {
+        apiKey: 'test-api-key',
+        authType: AuthType.USE_GEMINI,
+      },
+      mockConfig,
+    );
+
+    expect(GoogleGenAI).toHaveBeenCalledWith({
+      apiKey: 'test-api-key',
+      vertexai: undefined,
+      httpOptions: {
+        headers: expect.objectContaining({
+          'User-Agent': expect.any(String),
+        }),
+      },
+    });
+
+    expect(GoogleGenAI).toHaveBeenCalledWith(
+      expect.not.objectContaining({
+        apiVersion: expect.any(String),
+      }),
+    );
+  });
+
+  it('should pass apiVersion for Vertex AI when GOOGLE_GENAI_API_VERSION is set', async () => {
+    const mockConfig = {
+      getModel: vi.fn().mockReturnValue('gemini-pro'),
+      getProxy: vi.fn().mockReturnValue(undefined),
+      getUsageStatisticsEnabled: () => false,
+      getPreviewFeatures: vi.fn().mockReturnValue(false),
+    } as unknown as Config;
+
+    const mockGenerator = {
+      models: {},
+    } as unknown as GoogleGenAI;
+    vi.mocked(GoogleGenAI).mockImplementation(() => mockGenerator as never);
+    vi.stubEnv('GOOGLE_GENAI_API_VERSION', 'v1alpha');
+
+    await createContentGenerator(
+      {
+        apiKey: 'test-api-key',
+        vertexai: true,
+        authType: AuthType.USE_VERTEX_AI,
+      },
+      mockConfig,
+    );
+
+    expect(GoogleGenAI).toHaveBeenCalledWith({
+      apiKey: 'test-api-key',
+      vertexai: true,
+      httpOptions: {
+        headers: expect.objectContaining({
+          'User-Agent': expect.any(String),
+        }),
+      },
+      apiVersion: 'v1alpha',
+    });
+  });
 });
 
 describe('createContentGeneratorConfig', () => {

packages/core/src/core/contentGenerator.ts

@@ -130,6 +130,7 @@ export async function createContentGenerator(
     const customHeadersMap = parseCustomHeaders(customHeadersEnv);
     const apiKeyAuthMechanism =
       process.env['GEMINI_API_KEY_AUTH_MECHANISM'] || 'x-goog-api-key';
+    const apiVersionEnv = process.env['GOOGLE_GENAI_API_VERSION'];
 
     const baseHeaders: Record<string, string> = {
       ...customHeadersMap,
@@ -179,6 +180,7 @@ export async function createContentGenerator(
         apiKey: config.apiKey === '' ? undefined : config.apiKey,
         vertexai: config.vertexai,
         httpOptions,
+        ...(apiVersionEnv && { apiVersion: apiVersionEnv }),
       });
       return new LoggingContentGenerator(googleGenAI.models, gcConfig);
     }